Polymers of carbon monoxide and olefins, such as ethylene, have been known and available in limited quantities for many years. For example, polyketones are disclosed in Kirk-Othmer Encyclopedia of Chemical Technology, Second Edition, Vol. 12, p. 132, 1967, and in Encyclopedia of Polymer Science and Technology, 1968, vol. 9, 397-402. The low molecular weight coploymers in particular may be used as intermediates for the production of plastics, as components in blends with other polymers (such as waxes and greases) and as pour-point depressants for middle distillate petroleum fuel products. The higher molecular weight polymers have use and utility as premium thermoplastics for fibers, films, injection molding, compression molding or blowing applications.
High molecular weight linear polymers of carbon monoxide and ethylene in which monomer units occur in alternating order and which polymers consist of units of the formula ##STR2## can be prepared by using Group VIII metal organic phosphine compounds as a catalyst, such as palladium organic phosphine compounds. For example U.K. pat. No. 1,081,304, U.S. Pat. No. 3,689,460, and U.S. Pat. No. 3,694,412 disclose processes using palladium catalysts having monodentate alkyl phosphine ligands. Similar palladium catalysts having monodentate phosphine ligands are disclosed in the articles found in J. Am. Chem. Soc. 1982, 104, 3520-2, Organometallics 1984, 3, 866-70, Proc. Ind. Assoc. Cult. Sci. 1985, 68B, 1-5 and CHEMTECH 1986, 1, 48-51. European patent application No. 121,965 discloses a process for polymerizing CO and an alkenically unsaturated hydrocarbon using a Group VIII metal complex having bidentate phosphorous, arsenic or antimony ligands. Application of these catalysts to a monomer mixture which, in addition to carbon monoxide and ethylene, comprises at least one olefinically unsaturated hydrocarbon having the general formula C.sub.x H.sub.Y, which hydrocarbon has fewer than 20 carbon atoms and contains an olefinically unsaturated --CH.dbd.CH-- group, leads to the formation of polymers with units of the formula ##STR3## and units of the general formula ##STR4##
occurring randomly distributed within the polymer. The structure of the copolymers and "terpolymers" differs only in that in the case of the "terpolymers" a unit of ##STR5## is encountered at some random places in the polymer instead of a unit of ##STR6##
The polymers have excellent mechanical properties; especially, very high strength stiffness and impact resistance. However, the use of the Group VIII metal organic phosphine compounds as catalysts has the drawback that a considerable part of the metal catalyst remains in the polymers and cannot be removed therefrom by washing. The presence of a metal compound in the polymers is undesirable for two reasons. First, it poses problems to the processing of the generally high-melting polymers. This processing--for instance by injection molding--is done in the molten state with the polymer at a temperature at least 25.degree. C. above its melting point. The presence of a metal compound in the polymers makes them incapable of withstanding the high temperatures required in the processing. Serious discoloring and decomposition of the polymers is the result. Decomposition can further cause severe gelling which is a considerable hindrance to the processing of the polymers. As a rule the processing problems become worse as the content of metal compound in the polymers increases.
Second, it is undesirable that metal catalyst residue should be present in the polymers in that the catalyst is continually removed from the process of preparation and has to be supplemented to maintain the reaction. This reason concerns the cost of the catalyst. Although the concentration of catalyst in the process is small, when virtually all the metal employed ends up in the prepared polymer, it becomes a considerable expense to continually replace the catalyst especially for expensive Group VIII metals such as palladium. This may form a serious impediment to the polymer preparation being applied on a technical scale.